Disclosed herein are polymeric compositions comprising a per(phenylethynyl) arene derivative that can be used, for example, in various electronic applications such as, but not limited to, three dimensional (3D) packaging for IC chip assemblies. Also disclosed are substrates comprising same.
There is a need in the electronic fabrication industry for polymeric materials with materials of lower dielectric values for use as adhesives for 3D packaging of IC chip assemblies. However, the need for materials compatibility and dimensional stability over a wide range of conditions not only during ultimate end use, but also during further processing conditions leading to the finished integrated circuits, have presented significant problems. The properties of polymeric materials should conform to the rigid manufacturing requirements for integrated circuits or microchips in the electronic fabrication industry. One of the problems has been to make a polymeric thermoset system. This problem has been a difficult one to solve, particularly for those high Tg polymers wherein the desired temperature for reaction (cure) may range from 200-450° C.
Polymeric materials can have ∈ values in the range of 1.9-3.5, which is highly dependent on the structure. It is important that the polymeric material chosen for 3D packaging for IC chip and other applications, such as, for example, multichip module packaging, encapsulation and flat panel display applications, exhibit one or more of the chemical and physical properties described in Table I. The requirements provided in Table I are set forth by various IC manufacturers.
TABLE 1Summary of Low ∈, ILD Requirements Set by IC ManufacturersThermal StabilityDesirable thermal stability >400°C. in vacuum or forming gas(N2 with 4% H2).CVD Tungsten Deposition:400-480° C.CVD Copper Deposition:250-275° C.Dielectric Constant4.0 or lower, or 3.0 or lower, or 2.7 or lower.Moisture Absorption0.5 weight % or lessIsotropic DielectricNo anisotropy. Perpendicular and parallelConst.dielectric constants should be the same anduniform across the wafer.High Tg400° C. or greater; 300° C. or greaterwith a relatively high degree of crosslinking.Adhesion to Cu, Al,Depends upon application; adhesion promotersSiO2 and Sican also be used provided thermal stability isnot compromisedLow stressOptimum CTE (coefficient of thermalexpansion) would be the same as for SiO2PatternableShould be directionally etchable by RIE(reactive ion etching)Chemical CompatibilityExhibits little to no reactivity with metals;Possible reaction between Al lines andfluorinated polymers at elevated temperatures;Solubility of Cu in some polymersNo solvent absorptionNo swelling due to photoresist solvents.Compatibility with CMPDepends upon ultimate 3D process used(chemical-mechanicalpolishing)
Crosslinking has been recognized as one way to address the requirements of electronic materials polymers. Past attempts used various different approaches for crosslinking polymers. One such attempt is described, for example, in U.S. Pat. No. 6,060,170, which is assigned to the assignee of the present application. The '170 patent describes the use of poly(arylene ether) polymer compositions having aromatic groups grafted on the poly(arylene ether) backbone, whereby the grafts allow for crosslinking of the polymers in a temperature range of from 200 to 450° C. U.S. Pat. No. 5,658,994, which is also assigned to the assignee of the present application, describes the use of poly(arylene ethers) as low dielectric interlayers for the electronics industry wherein the poly(arylene ether) may be crosslinked, for example, by crosslinking itself, through exposure to temperatures of greater than approximately 350° C., or alternatively by providing a crosslinking agent. In addition, the '994 patent also teaches end capping the polymer with known end cap agents, such as phenylethynyl, benzocyclobutene, ethynyl and nitrile.
The references Hedberg, F. L.; Arnold, F. E.; J. Polym. Sci., Polym. Chem. Ed. (1976) 14, 2607-19 and Banihashemi, A.; Marvel, C. S.; J. Polym. Sci., Polym. Chem. Ed. (1977) 15, 2653-65 report the preparation of polyphenylquinoxalines with pendant phenylethynyl groups and their thermal cure via intramolecular cycloaddition and the heating of the 2,2′-di(phenylethynyl)biphenyl moiety to produce a 9-phenyldibenz[a,c]anthracene moiety which enhances the Tg of the polymer.
The references Hergenrother, P. M.; Macromolecules (1981) 14, (4) 891-897; and Hergenrother, P. M.; Macromolecules (1981) 14, (4) 898-904 report on the preparation of poly(phenylquinoxalines) containing pendent phenylethynyl groups along the backbone, where these materials were prepared for evaluation as precursors for high thermally stable thermosets.
U.S. Pat. No. 5,138,028 and EP Pat. Appl. No. 443352 A2 910828 describe the preparation of polyimides, polyamic acids, polyamic acid esters, polyisoimides which are end-capped with diarylacetylenes. The cured products can be used for encapsulation of electronic devices, as adhesives, and as moldings.
WO 97/10193 discloses various multi-phenylethynyl compounds which can be used for coating a wide variety of substrates such as computer chips.
The reference Zhou, Q et al., Polym. Preprint (1993) 34(1), 193-4, describes the preparation of carbon ladder polymers via the cyclization reactions of acetylenes.
U.S. Pat. No. 5,179,188 describes polymers (oligomers) such as those described in U.S. Pat. No. 5,114,780 which are end-capped with reactive groups having double and triple bonds.
WO 91/16370 (1991) describes crosslinkable fluorinated aromatic ether compositions.
PCT/US96/10812 teaches preparation of phenylethynylated monomers for use in preparing polymers which can thermally crosslinked.
Integrated circuit and chip manufacturing require suitable polymeric coatings and materials for packaging and other application. However, despite various attempts to provide appropriate crosslinking of polymers for these application, the art has not managed to solve the problem of providing polymeric materials that fulfill at least one of the following requirements: improved coefficient of thermal expansion (CTE), improved hardness, improved adhesion resistance wherein one or all of these requirements is achieved without a significant loss of substrate adhesion, thermal stability, or both.
All references cited herein are incorporated herein by reference in their entireties.